In data processing, it is desired to reduce buffer capacity, i.e. storage capacity provided for storing data during queuing.
In some known processors, incoming data traffic is admitted as quickly as possible without controlled admittance limitation, whereby limitations are given by processing capabilities. This will result in large requirements on buffer capacities in the processor. Also, data shaping can be used so that incoming data traffic is admitted to the processing element(s) of the processor so as to accomplish a constant bit rate, and/or a constant packet rate.
In a processor, a shaper might be used for controlling incoming traffic based on a first resource of the processor, for example the bit rate capacity, and another shaper might be used to control incoming traffic based on a second resource of the processor, for example the data packet rate capacity. Such shapers usually have some credit parameter, for example in the form of a token bucket, based on which packets are admitted to the processing element(s) of the processor. The credit values are increased periodically with predetermined amounts, data packets are not admitted unless credit values of the shapers have reached a limit value, and the credit values are decreased when data packets are admitted. In such a processor, bursts might occur in the processor reasons illustrated by the following example: After a sequence of packets consuming a relatively large amount of the first resource and a relatively small amount of the second resource, e.g. relatively long data packets, the credit value of one of the shapers will reach a relatively high level. If such a packet sequence consuming a lot of the first resource and little of the second resource is followed by a sequence of packets consuming a relatively small amount of the first resource, e.g. relatively short data packets, a burst of packets will be permitted until the credit value having reached a relatively high level falls below the limit for admittance of packets. The risk of such data bursts will require a large buffer capacity downstream of the shapers.